1. Field of the Invention
Nortriptyline is a tricyclic antidepressant which finds extensive use. The therapeutic range for the drug is from about 50 to 175 ng/ml. Lower dosages do not have significant effect and overdosages have substantial side effects which can be life-threatening. Overdoses can result in convulsions, coma, cardiac arrhythmias, and anticholinergic signs, such as mydriasis and tachycardia.
It is found that the rate of metabolism of the drug can vary widely with individuals, as well as the sensitivity of the individual to the drug. It is therefore necessary to insure proper dosage levels to monitor the plasma level, so that a therapeutic dosage level may be maintained.
In monitoring the dosage level, it is desirable that there be a simple, accurate, rapid technique for measuring the nortriptyline level, which can distinguish nortriptyline from other drugs and metabolites of nortriptyline, which might otherwise give an erroneous value of the nortriptyline level.